1. Field of the Invention
The present invention relates to a coded data transfer control method for controlling a timing of a transfer operation of coded data and, more particularly, the technical field of a coded data transfer control method which controls a transfer timing of compression-coded data obtained by the MPEG2 scheme and constitutes an MPEG2 transport stream to output the MPEG2 transport stream.
2. Description of the Related Art
In recent years, digital broadcasting in which video data or audio data is digitized and multiplexed to be transmitted is becoming more popular. In the digital broadcasting, an MPEG (Moving Picture Expert Group) scheme is employed as a compression/encoding scheme. In particular, the MPEG 2 scheme, which is capable of supporting a wide range of applications and achieving data transmission with high quality and high efficiency, receives attention as a standard compression/encoding scheme in digital broadcasting. In digital broadcasting using the MPEG 2 scheme, data on a plurality of programs is multiplexed in an MPEG 2 transport stream (hereinafter, referred to as MPEG2-TS) and transmitted. A receiving system for receiving the data is configured to selectively extract desired data. In this storage and reproduction system, arbitrary coded data included in the MPEG2-TS stored in a storage device is transferred at a predetermined timing and controlled such that the transferred coded data is decoded and displayed at a predetermined timing, so that video data can be reproduced under desired conditions.
In the meantime, in the case where video data stored in a storage device is reproduced in the storage and reproduction system, it is desirable that a special reproduction processing function supporting fast forward winding or rewinding is provided. The video data multiplexed on the MPEG2-TS is comprised of a large number of pictures, and the respective pictures function as access units to be accessed in normal reproduction and random reproduction. Therefore, in reproduction, picture data to be displayed must be specified, and the picture data must be sequentially transferred to an MPEG2 decoder at transfer timings conforming to reproduction. In particular, in special reproduction, picture data to be displayed must be specified, and the picture data must be sequentially transferred to the MPEG2 decoder at transfer timings conforming to special reproduction.
However, in a transfer operation of MPEG2 picture data, after transfer is started, all picture data are inputted to a buffer on the decoder side, a certain period of time is required until decoding and display of the picture data are completed. On the other hand, with respect to the respective picture data, display timings corresponding to reproduction are set. As described above, since a certain period of time is required to perform the transfer operation, the picture data may be behind the display timing of the predetermined picture data. Therefore, a blank period until the first picture is displayed after reproduction is started becomes long, a person who watches the reproduced image feels incompatibility disadvantageously.